Apple & Atari ML Monitor

I use both an Atari 800XL and an Apple IIe. It's very simple to enter the monitor on the Apple: Just enter CALL —151. Is there a simple method like this on the Atari?

James J. Brennan, Jr.

No, because the Atari does not have a built-in machine language monitor. Few personal computers designed since the late 1970s include ML monitors, since manufacturers feel that only a minority of owners are interested in ML programming and monitors take up valuable ROM space. The Apple IIe and IIc retain an ML monitor because they are enhanced versions of the Apple II, originally designed as a kit-built computer for hobbyists in 1976. The Commodore PET, introduced in 1977, also incorporates an ML monitor. But since then, the only computers introduced for the mass market with a built-in monitor have been the Commodore Plus/4 and 16. Most manufacturers today prefer to eliminate the monitor and use the extra ROM space for a more powerful BASIC or operating system.

Excellent monitors are available separately for the Atari, however. The Atari Assembler Editor cartridge, Optimized Systems Software's EASMD and MAC/65, and several other commercial assemblers include monitors. The Monkey Wrench, by Eastern House Software, adds several commands to BASIC and includes a Commodore-style monitor that you can call from BASIC. However, it works only in the right cartridge slot of an Atari 800, not with the 800XL.